I have posted here many times about the practice of many Internet Service Providers of blocking email at the server level before it reaches the customer.
Touted as a benevolent spam control big brother protecting us from spam, this cure is killing the patient.
Well, the "cure" is spreading. I doubt that there are any ISPs left now that allow you to choose what you will be allowed to read. I used to think that Earthlink was one that took email delivery seriously. Many times I had been told that Earthlink does not block email. That was a lie. Thanks to Tom Merrit for providing me with proof.
They do, in fact, block email at the server level.
Any ISP that does this makes their email system unreliable because all spam filters and other such strategies are flawed. A certain percentage of important legitimate mail is always blocked.
One of the spam list services that Earthlink uses own documentation shows how easily a legitimate user can be tagged as a spammer:
"listings are immediate and, in the case of known spam gangs, are preemptive. The SBL does not require warnings or have a 'grace period' and does not require physical evidence of spam received from any specific IP to qualify a listing (in the case of known spam gangs, any IPs under their control are listed on sight). Warnings are however normally sent to block owners and/or Upstreams before listing large netblocks."
They just block whole IP ranges willy nilly with no evidence

This practice hurts our business and our reputation for responsive support. How may customers or potential customers who are blocked from emailing Autonerdz is unknown. Those who do get bounce back messages probably do not jump through all the hoops required to get Earthlink's permission to email us. Those who themselves have similar issues may not even receive the bounceback notice and assume we are just unresponsive.
I am looking into ways to legally compel Earthlink to deliver mail. I'm not too hopeful though.
The more people that are aware of this practice, perhaps the more likely others will follow.
I would change ISPs but since they all do this, that would be all for not. To those of you that have had email delivery issues where I have recommended Earthlink to, as a solution....My apologies. They are no better than all the rest.